Electrowetting refers to a phenomenon where by changing the voltage between a droplet and an insulating substrate, the wettability of the droplet on the insulating substrate is changed (i.e., the contact angle is changed), such that the droplet is deformed or displaced. Wetting means that liquid can spread on a solid surface, and the contact area tends to increase, that is, the adhesion of the liquid to the solid surface is greater than the cohesion of the liquid. Non-wetting means that liquid cannot spread on a solid surface, and the contact area tends to shrink to form a spherical shape, that is, the adhesion of the liquid to the solid surface is smaller than the cohesion of the liquid.
Electrowetting display technology makes use of the electrowetting phenomenon to control an ink droplet as a pixel. For example, when the ink droplet shrinks to a dot shape, the pixel presents white color; and when the ink droplet spreads on the pixel surface, the pixel presents the color of the ink. Electrowetting display technology attracts more and more attention due to the advantages of bistable displaying, good reflectivity, low power consumption, broad temperature range, sufficiently quick response speed and so on. Therefore, there is a need to continuously improve the display performances of the electrowetting display device.